Polyurea macromer and latexes thereof

ABSTRACT

The present invention is a composition comprising a) a stable aqueous dispersion of polymer particles having one or more structural units of i) a polyurea macromer; and ii) an acrylate, a methacrylate, a vinyl ester, or a styrene monomer, or a combination thereof; and/or b) an 5 aqueous mixture of a i) polyurea macromer polymer particles; and b) acrylate, methacrylate, vinyl ester, or styrenic polymer particles, or a combination thereof, wherein the polyurea macromer is characterized by the following formula I: 
                         
10 where A 1 , A 2 , R 1 , R 2 , and R 3  are as defined herein. In another aspect, the present invention is the compound of Formula I. Compositions prepared using the compound of the present invention can be used to form coatings with excellent balance of low temperature film formation, hardness, and flexibility.

BACKGROUND OF THE INVENTION

The present invention relates to a polyurea macromer (PUM), which isuseful in the preparation of aqueous dispersions of a variety ofemulsion polymers.

Aqueous dispersions of acrylic polymers and polyurethanes generallyserve similar market segments. Polyurethane dispersions (PUDs) typicallyoffer superior balance of film formation, flexibility, and hardness overacrylic dispersions in coatings applications, and a superior balance oftoughness, abrasion resistance, and mechanical flexibility in adhesivesapplications. Acrylics, on the other hand, can provide exceptionalexterior durability and chemical resistance more cost effectively thanPUDs.

The different performance profiles of PUDs and acrylics can beattributed to significant differences in their polymer chainarchitecture. The pressure to balance cost and performance has lead PUDusers to evaluate PUD/acrylic blends and hybrid, with limited success.(See, for example, R. A. Brown et al., “Comparing and contrasting theproperties of urethane/acrylic hybrids with those of correspondingblends of urethane dispersions and acrylic emulsions,” Progress inOrganic Coatings 2005, 52 (1), 73-84; and H. T. Lee et al., “Synthesisand properties of aqueous polyurethane/polytert-butylacrylate hybriddispersions,” Journal of Polymer Research 2005, 12 (4), 271-277; andU.S. Pat. No. 5,650,159.)

It would be an advance in the art to find a cost effective way ofachieving the desired properties of acrylics and PUDs.

SUMMARY OF THE INVENTION

The present invention is a compound of the following formula I:

wherein n is 1 to 20;

R¹, R², and R³ are each independently a C₂-C₂₀ alkanediyl group, aC₃-C₂₀ cycloalkanediyl group, a C₆-C₂₀ arenediyl group, or a C₇-C₂₀aralkanediyl group;

X and Y are independently O or NR⁴, wherein R⁴ is H or C₁-C₆-alkyl, withthe proviso that at least one of X and Y is NH;

at least one of A¹ and A² is —C(O)—(Z)_(m)—R⁵; —CH₂—CH(OH)R⁶;—CR⁷═CH—C(O)—O—(CH₂)_(p)R⁸; —C(O)—Y′—(CH₂)_(p)R⁹; or CH₂—CH₂—C(O)—O—R¹⁰;

wherein each R⁵ is independently a C₂-C₂₀ alkyl group, a C₃-C₂₀cycloalkyl group, a C₆-C₂₀ aryl group, or a C₇-C₂₀ aralkyl group, withthe proviso that at least one R⁵ is functionalized with a carboxylicacid group or a polymerizable olefin group or both;

each R⁶ is independently —CH₂-acrylate, —CH₂-methacrylate, or—(CH₂)_(p)—COOH;

each R⁷ is independently H or CH₃;

each R⁸ is independently an acrylate group, a methacrylate group, orCOOH;

each R⁹ is independently an acrylate group or a methacrylate group;

each R¹⁰ is independently H or —CH₂CH═CH₂;

Y′ is O or NR⁴;

m is 0 or 1;

each p is independently from 2 to 6; and

the compound has an M_(n) in the range of 500 to 8,000 Daltons.

Coatings of acrylic emulsion polymers functionalized with the compoundof the present invention exhibit an excellent balance of low temperaturefilm formation, hardness, and flexibility.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a compound of the following formula I:

wherein n is 1 to 20;

R¹, R², and R³ are each independently a C₂-C₂₀ alkanediyl group, aC₃-C₂₀ cycloalkanediyl group, a C₆-C₂₀ arenediyl group, or a C₇-C₂₀aralkanediyl group;

X and Y are independently O or NR⁴, wherein R⁴ is H or C₁-C₆-alkyl, withthe proviso that at least one of X and Y is NH;

at least one of A¹ and A² is —C(O)—(Z)_(m)—R⁵; —CH₂—CH(OH)R⁶;—CR⁷═CH—C(O)—O—(CH₂)_(p)R⁸; —C(O)—Y′—(CH₂)_(p)R⁹; or CH₂—CH₂—C(O)—O—R¹⁰;

wherein each R⁵ is independently a C₂-C₂₀ alkyl group, a C₃-C₂₀cycloalkyl group, a C₆-C₂₀ aryl group, or a C₇-C₂₀ aralkyl group, withthe proviso that at least one R⁵ is functionalized with a carboxylicacid group or a polymerizable olefin group or both;

each R⁶ is independently —CH₂-acrylate, —CH₂-methacrylate, or—(CH₂)_(p)—COOH;

each R⁷ is independently H or CH₃;

each R⁸ is independently an acrylate group, a methacrylate group, orCOOH;

each R⁹ is independently an acrylate group or a methacrylate group;

each R¹⁰ is independently H or —CH₂CH═CH₂;

Y′ is O or NR⁴;

m is 0 or 1;

each p is independently from 2 to 6; and

the compound has an M_(n) in the range of 500 to 8,000 Daltons.

Preferably, X and Y are each NH; preferably the compound has an M_(n) inthe range of from 1000 Daltons to 6000 Daltons, more preferably to 3000Daltons. Preferably R¹ is 1,6-hexanediyl,

Preferably, R² and R³ are each independently C₂-C₁₀ linear or branchedalkanediyl groups, benzenediyl groups, benzenedimethanediyl groups, orcyclohexanediyl groups; more preferably, R² and R³ are eachindependently linear or branched C₃-C₁₀-alkanediyl groups; mostpreferably, R² and R³ are each —CH₂CH(CH₃)— groups.

Preferably, m is 0; preferably n is 2 to 10.

It is preferable that each of the A¹ and A² groups is functionalizedwith a carboxylic acid group, a polymerizable olefin group, or both. Ifonly one of A¹ and A² is functionalized with a carboxylic acid groupand/or a polymerizable olefin group, the other of A¹ and A² may be theunreacted primary amine or a remnant of an aliphatic, cycloaliphatic,aromatic compound optionally containing O, N, or S functionality, havinga molecular weight of not more than 500, and is reactive with a primaryamine (e.g., a C₁-C₂₀ alkyl halide) or an isocyanate (e.g., a phenol ora C₁-C₂₀ alcohol) Examples of suitable R⁵ groups include:

where R¹¹ is a linear or branched C₁-C₁₅-alkyl group; preferably aC₈-C₁₀-linear or branched alkyl group.

More preferred R⁵ groups include:

Preferably, R⁶ is —CH₂-methacrylate or —CH₂CH₂—COOH, with—CH₂-methacrylate being more preferred; R⁷ is preferably H; R⁸ ispreferably methacrylate or COOH; R⁹ is preferably methacrylate; and p ispreferably 2 or 3.

A preferred compound is represented by the following formula II:

Compound I (where m=0; X and Y are each NH; R²═R³; and each R⁴, togetherwith the carbon atoms to which they are attached, form a carbonyl group)can be prepared as shown in Scheme 1:

In a first step, a diisocyanate is reacted with a stoichiometric excessof a diamine to form a polyurea diamine macromer intermediate, themolecular weight of which can be controlled by the stoichiometry of thestarting materials. In a second step, the intermediate is reacted withone or more electrophiles, preferably two distinct electrophiles (E¹ andE²), preferably added in separate steps, to form the PUM with end groupsA¹ and A². At least one of E¹ and E² is functionalized with a carboxylicacid group or a polymerizable olefinic group or both. Examples ofsuitably functionalized electrophiles include anhydrides such as1,2,4-benzenetricarboxylic acid anhydride, 2-(dodecen-1-yl)succinicanhydride, succinic anhydride, maleic anhydride, methacrylic anhydride,acrylic anhydride, and itaconic anhydride; acrylate and methacrylateepoxides such as glycidyl methacrylate; acrylol and methacrylol halidessuch as methacrylol chloride; and alkyl halides such as bromopentane andbromohexane.

E¹ and E² are preferably anhydrides added in separate steps.

Examples of suitable diisocyanates include isophorone diisocyanate(5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl cyclohexane),1,6-hexamethylene diisocyanate, 2,4-diisocyanato-1-methyl-benzene, andmethylene diphenyl diisocyanates.

Examples of suitable diamines include C₂-C₂₀ alkanediamines such as1,2-ethanediamine, 1,2-propanediamine, 1,3-propanediamine,1,6-hexanediamine, and 1,8-octanediamine; C₃-C₂₀-cycloalkanediaminessuch as 1,4-cyclohexanediamine and isophoronediamine;C₆-C₂₀-arenediamines such as 1,4-diaminobenzene; andC₇-C₂₀-aralkanediamines such as 1,4-phenylenedimethanamine and4,4′-methylenedianiline.

The diamine is preferably contacted with the diisocyanate in thepresence of a polar solvent such as dimethylacetamide or isopropanol toproduce an intermediate with a number average molecular weightpreferably from 300, more preferably from 500, and most preferably from1000 Daltons, to preferably 7000 Daltons, more preferably to 5000Daltons, and most preferably to 3000 Daltons.

It is also possible to contact an excess of the diisocyanate with thediamine to obtain a second subclass of intermediate that can be furtherreacted with one or more nucleophiles, preferably two nucleophiles (Nuc¹and Nuc²), preferably added in separate steps, to form the intermediateas shown in Scheme 2. At least one of the nucleophiles is functionalizedwith a carboxylic acid group or a polymerizable olefinic group or both.Examples of suitably functionalized nucleophiles include hydroxyethylmethacrylate, hydroxypropyl methacrylate, and 3-hydroxypropanoic acid.

The PUM of the present invention can be conveniently contacted with oneor more ethylenically unsaturated monomers such as acrylate,methacrylate, a vinyl ester, and styrenic monomers to form aPUM-containing emulsion polymer.

Examples of suitable acrylate monomers include ethyl acrylate, butylacrylate, 2-propylheptyl acrylate, and 2-ethylhexyl acrylate; examplesof suitable methacrylates include methyl methacrylate, butylmethacrylate, acetoacetoxyethyl methacrylate, and ureido methacrylate;examples of suitable vinyl esters include vinyl acetate and vinyl estersof neodecanoic acid; example of suitable styrenics include styrene,vinyl toluenes, and a-methylstyrene. Other ancillary monomers may beused to make the PUM-containing emulsion polymer, including acrylamides,acrylonitrile; carboxylic acid monomers and salts thereof (e.g.,methacrylic acid, acrylic acid, and itaconic acid, and salts thereof);sulfur acid monomers and salts thereof (e.g.,2-acrylamido-2-methylpropanesulfonic acid and styrene sulfonic acid andsalts thereof); and phosphorus acid monomers and salts thereof (e.g.,phosphoethyl methacrylate and methacryloyloxyethyl phosphonic acid andsalts thereof.)

The contact can occur during or after, preferably during thepolymerization of the other monomers to form a copolymer of the PUM andthe other monomers or a non-covalently bonded mixture of the PUM and theemulsion copolymer, or a combination thereof. Accordingly, in a secondaspect, the present invention is a composition comprising a) a stableaqueous dispersion of polymer particles having one or more structuralunits of i) the PUM; and ii) an acrylate, a methacrylate, a vinyl ester,or a styrene monomer, or a combination thereof; and/or b) an aqueousmixture of i) PUM polymer particles; and ii) acrylate, methacrylate,vinyl ester, or styrenic polymer particles, or a combination thereof. Asused herein, the term “structural unit” refers to the remnant of themonomer or macromer after polymerization. Thus, a structural unit of amacromer with A²=—C(O)—R⁵ where R⁵ is

is illustrated as follows:

wherein the dotted lines are the points of attachment to the polymerbackbone.

A non-covalently bonded mixture of the PUM and the emulsion copolymercan be prepared by contacting a) an aqueous dispersion of abase-neutralized PUM having a solids content preferably in the range of20 to 50 weight percent, with b) the emulsion copolymer, which ispreferably adjusted to a basic pH. The resultant mixture is preferably ananodispersion with Z-average particle size preferably in the range offrom 10 nm to 500 nm, more preferably to 100 nm, and most preferably to50 nm. The aqueous dispersion of the base-neutralized PUM is preferablyprepared by contacting together a base, preferably NaOH or KOH, with thePUM in the presence of water at and advanced temperature, preferably inthe range of 60° C. to 100° C.

Preferably, the polymer particles comprise from 2 to 50, more preferably30 weight percent structural units of the PUM and from 50, morepreferably from 70 to 98 weight percent structural units of theacrylate, the methacrylate, the vinyl ester or the styrene, orcombinations thereof. Many properties of the final polymer can be tunedby changing the chemistry used to build the macromer. The approachdescribed herein provides a convenient way of incorporating PUD featuresinto an acrylic backbone. Specifically, the macromer of the presentinvention provides a useful way to tune hydrogen-bonding strength,hydrophilicity/hydrophobicity balance of the colloid, and location ofthe macromer in the latex particle. This approach is useful to solvecompatibility issues observed in PUD/acrylic blends and results in animproved minimum film forming temperature/hardness balance. This latterproperty is critical as more and more coatings move towards zerovolatile organic compound (0 VOC) requirements.

EXAMPLES Intermediate 1—Synthesis of Polyurea Oligomer Precursor,M_(n)=1480 Daltons

Dimethylacetamide (DMAc, 300 mL) and 1,2-propanediamine (1,2-PDA, 16 g)were charged under N₂ into a 1-L, 4-neck flask equipped with an overheadstirrer, a condenser, and an addition funnel. Isophorone diisocyanate(IPDI, 40 g) was transferred to the addition funnel and added to thereaction flask over 1 h while maintaining the temperature at 30° C. withan ice bath. The oligomer solution was used as is for the next step.

Intermediate 2—Synthesis of Polyurea Oligomer Precursor, M_(n)=5040Daltons

DMAc (425.75 g) and 1,2-PDA (24 g) were charged under N₂ into a 1-L,4-neck flask equipped with an overhead stirrer, a condenser, and anaddition funnel. The solution was stirred at 250 rpm at roomtemperature. IPDI (67.91 g) was transferred to the addition funnel andadded to the react over 18 min. When the temperature exceeded 30° C. thereaction vessel was blown with cold air to remove heat. Over the courseof the reaction the solution temperature reached 45.6° C. When theaddition was finished, the funnel was rinsed into the reaction flaskusing 10.7 g of DMAc.

Intermediate 3. Synthesis of Polyurea Oligomer Precursor, M_(n)=1620Daltons

DMAc (170 g) and 1,2-PDA (20 g) were charged under N₂ into a 500-mL,4-neck flask equipped with an overhead stirrer, a condenser and anaddition funnel. The solution was stirred at 300 rpm at 13° C.Separately, ISONATE™ OP-50 MDI (A Trademark of The Dow Chemical Companyor its Affiliates, 55 g) and DMAc (55 g) was prepared and transferred tothe addition funnel and added to the reaction flask over 13 min. Overthe course of the reaction the solution temperature reached 24° C., atwhich time stirring was increased to 420 rpm. Additional DMAc (201 g)was added to the final mixture.

Example 1 Synthesis of Polyurea Macromer, M_(n)=1960 Daltons

Trimellitic anhydride (8.65 g) was dissolved in dry dimethylformamide(70 mL, DMF) and added to a reaction flask containing the solution ofIntermediate 1 in DMAc at 50° C. over 30 min. A solution of dodecen-1-ylsuccinic anhydride (14.73 g) in DMAc (50 mL) was then added dropwise tothe reaction flask over 15 min while temperature was maintained at 50°C. Upon completion of the addition, the reaction mixture was cooled toroom temperature, filtered, and precipitated with cold acetone. Thecoarse solid was redissolved in methanol and precipitated a second timein cold acetone. After filtration, the coarse white solid was dried at35° C. in vacuo.

Example 2 Synthesis of Polyurea Macromer M_(n)=5370 Daltons

Into a 1 L, 4-neck flask equipped with an overhead stirrer and acondenser was added Intermediate 2 (112.17 g). The solution was stirredat 250 rpm and the reaction was heated to 50° C. Maleic anhydride (0.488g) was added over 10 min followed by addition of trimellitic anhydride(1.13 g) over 2 min. The reaction was cooled to room temperature and wasprecipitated in acetone at −10° C. The sample was then filtered,transferred to a graduated jar, and filled to a total volume of 300 mLwith MeOH. The slurry was warmed to 50° C. and the solid dissolved over1 h. The sample was precipitated again in cold acetone. Afterfiltration, the coarse white solid was dried at 35° C. in vacuo.

Example 3 Synthesis of Polyurea Macromer M_(n)=1800 Daltons

Into a 1-L, 4-neck flask equipped with an overhead stirrer and acondenser was added a compound prepared as Intermediate 1 (400 g). Thesolution was stirred at 250 rpm and the reaction was heated to 50° C.Maleic anhydride (6.21 g) was added all at once followed by addition oftrimellitic anhydride (12.7 g) all at once. The reaction was cooled toroom temperature and was precipitated in acetone at −10° C. The samplewas then filtered, transferred to a graduated jar, filled to a totalvolume of 400 mL with MeOH and stirred overnight to dissolve. The samplewas precipitated again in cold acetone. After filtration, the coarsewhite solid was dried at 35° C. in vacuo.

Example 4 Synthesis of Polyurea Macromer M_(n)=2100 Daltons

Intermediate 3 (142 g, 15% oligomer), was charged in a 500-mL, 4-neckflask equipped with an overhead stirrer and a condenser. The solutionwas stirred at 350 rpm and the reaction vessel was heated to 50° C.Dodecen-1-yl succinic anhydride (4.23 g) was added to the vessel, rinsedin with DMAc (24.0 g). The reaction temperature was held constant for 20min. Trimellitic anhydride (3.07 g) was added to DMAc (21.0 g) and wasthen added over 10 min to the reactor at 50° C., after which time thereaction was cooled to room temperature and the product was precipitatedby slow dripping into 4 L of acetone at room temperature. The sample wasthen filtered and rinsed with acetone and the filter cake wastransferred to a jar and dried at 35° C. in vacuo.

Example 5 Synthesis of Polyurea Macromer M_(n)=1900 Daltons

Into a 1-L, 4-neck flask equipped with an overhead stirrer and acondenser was added Intermediate 1 (100 g) followed by DMF (46.27 g).The solution was stirred at 250 rpm and the reaction was heated to 50°C. Trimellitic anhydride (6.12 g) was added to the reactor as a powderand dissolved rapidly over a few minutes. After 30 min, the reaction wascooled to room temperature and was precipitated in cold acetone. Thesample was then filtered, transferred to a graduated jar, and filled toa total volume of 400 mL with MeOH. The slurry was warmed to 50° C. andthe solid dissolved over 1 h. The sample was precipitated again in coldacetone. After filtration, the coarse white solid was dried at 35° C. invacuo.

Dynamic light scattering was used to measure Z-average particle size inthe following examples.

Example 6 Polyurea Macromer Stabilized Binder (60 BA/20 MMA/20 PUM)

Into a 1-L, 4-neck flask equipped with an overhead stirrer and acondenser was added the PUM as prepared in Example 1 (20 g), NaOH (50wt. % in water, 3 g) and deionized water (90 g). The reactor was heatedto 85° C. for 30 min with agitation at 120 rpm under N₂. Ammoniumpersulfate (0.52 g) was dissolved in deionized water (20 g) was added ina single shot to the reactor. The temperature decreased to 82° C. andwas allowed to increase to 85° C. over 2 min. A butyl acrylate/methylmethacrylate monomer mixture (BA/MMA (60 g/20 g)) was added to thekettle over 1 h, after which time deionized water (5 g) was added as arinse. The contents of the reactor were held at temperature for 30 minfollowed by cooling to 65° C. over 20 min. Next, t-amyl hydroperoxide(0.1 g in 1 mL of water) and a solution of FeSO₄.7H₂O/tetrasodiumethylenediamine tetraacetic acid (0.61 mg of each in 1 mL deionizedwater), were added directly to the kettle. Subsequently, Bruggolite FF6M reducing agent (0.045 g in 3 mL of DI water) was added over 30 min.The latex was filtered through a 100-mesh filter and the coagulum wasisolated and weighed. The measured particle size was 108 nm, final pHwas 8.7 and the solids were 40.6%. A Minimum Film Formation Temperature(MFFT) below 0° C. and a Koenig hardness of 26 s were obtained on adried film from the emulsion. Storage modulus of the material at 140° C.as measured by Dynamic Mechanical Analysis (DMA) was 100 MPa.

Example 7 Polyurea Macromer Stabilized Binder (60 BA/20 MMA/20 PUM)

Into a 500-mL, 4-neck flask equipped with an overhead stirrer and acondenser was added PUM as prepared in Example 2 (9 g), NaOH (50 wt. %in water, 0.828 g) and deionized water (46.57 g). The reactor was heatedto 85° C. for 30 min with agitation at 120 rpm under N₂. Ammoniumpersulfate (0.232 g) was dissolved in deionized water (6 g) and wasadded in a single shot to the reactor. The temperature decreased to 82°C. and was allowed to increase to 85° C. over 2 min. A butylacrylate/methyl methacrylate monomer mixture (BA/MMA (27 g/9 g)) wasadded to the kettle over 1 h. The contents of the reactor were held attemperature for 30 min followed by cooling to 65° C. over 20 min. Next,t-amyl hydroperoxide (0.045 g in 1.75 mL of water) and a solution ofFeSO₄.7H₂O/tetrasodium ethylenediamine tetraacetic acid (0.28 mg of eachin 1 mL deionized water), were added directly to the kettle.Subsequently, formaldehyde-free reducing agent, Bruggolite FF6 M (0.02 gin 1.75 mL of DI water) was added over 30 min. The latex was filteredthrough a 100-mesh filter and the coagulum was isolated and weighed. Themeasured particle size was 113 nm, final pH was 7.14 and the solids were41.49%. A Minimum Film Formation Temperature (MFFT) below 0° C. and aKoenig hardness of 42 s were obtained on a dried film from the emulsion.

Example 8 Polyurea Macromer Stabilized Binder (60 BA/28.9 MMA/11.1 PUM)

Into a 500-mL, 4-neck flask equipped with an overhead stirrer and acondenser was added PUM as prepared in Example 4 (4.5 g), NaOH (50 wt. %in water, 0.71 g) and deionized water (46.57 g). The reactor was heatedto 85° C. for 30 min with agitation at 120 rpm under N₂. Ammoniumpersulfate (0.232 g) was dissolved in deionized water (6 g) and wasadded in a single shot to the reactor. The temperature decreased to 82°C. and was allowed to increase to 85° C. over 2 min. A butylacrylate/methyl methacrylate monomer mixture (BA/MMA (27 g/11.7 g)) wasadded to the kettle over 1 h. The contents of the reactor were held attemperature for 30 min followed by cooling to 65° C. over 20 min. Next,t-amyl hydroperoxide (0.045 g in 1.75 mL of water) and a solution ofFeSO₄.7H₂O/tetrasodium ethylenediamine tetraacetic acid (0.28 mg of eachin 1 mL deionized water), were added directly to the kettle.Subsequently, Bruggolite FF6 M reducing agent (0.02 g in 1.75 mL of DIwater) was added over 30 min. The latex was filtered through a 100-meshfilter and the coagulum was isolated and weighed. The measured particlesize was 103 nm, final pH was 6.66 and the solids were 41.63%. A MinimumFilm Formation Temperature (MFFT) below 0° C. and a Koenig hardness of5.6 s were obtained on a dried film from the emulsion.

Example 9 Polyurea Macromer Stabilized Binder (60 BA/20 MMA/20 PUM)

Into a 500-mL, 4-neck flask equipped with an overhead stirrer and acondenser was added PUM as prepared in Example 4 (9 g), NaOH (50 wt. %in water, 1.21 g) and deionized water (46.57 g). The reactor was heatedto 85° C. for 30 min with agitation at 120 rpm under N₂. Ammoniumpersulfate (0.232 g) dissolved in deionized water (6 g) was added in asingle shot to the reactor. The temperature decreased to 82° C. and wasallowed to increase to 85° C. over 2 min. A butyl acrylate/methylmethacrylate monomer mixture (BA/MMA (27 g/9 g)) was added to the kettleover 1 h. The contents of the reactor were held at temperature for 30min followed by cooling to 65° C. over 20 min. Next, t-amylhydroperoxide (0.045 g in 1.75 mL of water) and a solution ofFeSO₄.7H₂O/tetrasodium ethylenediamine tetraacetic acid (0.28 mg of eachin 1 mL deionized water), were added directly to the kettle.Subsequently, Bruggolite FF6 M reducing agent (0.02 g in 1.75 mL of DIwater) was added over 30 min. The latex was filtered through a 100-meshfilter and the coagulum was isolated and weighed. The measured particlesize was 182 nm, final pH was 6.35 and the solids were 42.43%. A MinimumFilm Formation Temperature (MFFT) of 3° C. and a Koenig hardness of 39 swere obtained on a dried film from the emulsion. Storage modulus of thematerial at 140° C. as measured by Dynamic Mechanical Analysis (DMA) was100 MPa.

Comparative Example 1 Control Emulsion 1 (60BA/36.8MMA/3.2MAA//0.3 DS-4)

A process similar to that described for the preparation of the polyureamacromer-stabilized emulsion of Example 5 was followed. In thiscomparative example, sodium dodecylbenzene sulfonate (1.333 g, 22.5%active, DS-4), methacrylic acid (3.23 g), NaOH (50 wt. % solution, 0.54g) and water were initially added to the flasks and heated to 85° C.under N₂. The rest of the reaction was identical to the PUM-stabilizedemulsion synthesis. The measured particle size was 105 nm, final pH was6 and the solids were 43.1%. An MFFT of 7° C. and a Koenig hardness of5.6 s was obtained on a dried film from the emulsion. Storage modulus ofthe material at 140° C. as measured by DMA was 0.1 MPa.

Comparative Example 2 Control Emulsion 2 (60 BA/38 MMA/2 MAA)

A monomer emulsion (ME) was prepared by adding water (127 g), FES-32surfactant (9.52 g of a 30% FES-32 solution), butyl acrylate (162 g),methyl methacrylate (102.5 g) and methacrylic acid (5.5 g). An ME seed(9.9 g) was removed from the ME. In the reactor kettle, water (103 g),FES-32 surfactant (1.9 g of a 30% FES-32 solution), and sodium carbonatebuffer (5.1 g of a 5.6% solution in DI water) were added and the kettlewas heated to 89° C. At 89° C., the ME seed (9.9 g) and ammoniumpersulfate (0.99 g in 3.0 g of deionized water) were added sequentiallyto the reactor in two separate shot additions. After 2 min, the rest ofthe ME and ammonium persulfate (0.15 g in 11.9 g of deionized water)were fed to the reactor over 90 min. The reactor was temperature wasmaintained isothermal at 89° C. over the course of the feed. Once the MEand ammonium persulfate feeds were complete, deionized water (5.0 g) wasadd to the ME container to rinse the remaining monomer into the reactor.The reactor temperature was then allowed to cool to 70° C. over 10 min.At 70° C., a solution of FeSO₄.7H₂O (1.95 g of a 0.15 wt. % deionizedwater solution) was combined with additional deionized water (2.6 g) andadded directly to the kettle. The reactor kettle was allowed to furthercool to 60° C. over 15 min. After cooling the reactor to 60° C., anemulsified solution of t-amyl hydroperoxide (0.1 g), FES-32 surfactant(0.05 g of a 30% FES-32 solution) and deionized water (1.49 g) was addeddirectly to the kettle. Subsequently, isoascorbic acid (0.054 g in 3.0 gof deionized water) was added over 15 min. The latex was filteredthrough a 100-mesh filter and the coagulum was isolated and weighed. Themeasured particle size was 120 nm, the final pH was 4.5 and the solidscontent was 49.5%. An MFFT of 0° C., a Koenig hardness of 2.8 s andwater whitening value of 0 after 20 min of water exposure were measuredon a dried film from the emulsion.

Water whitening is a qualitative test in which a droplet of water isplaced onto a dry clear film of the emulsion. After a certain period oftime, the water droplet is whipped out of the surface and the filminspecting visually for whitening (0 is no whitening while 10 iscomplete whitening of the film). Non-covalently bonded mixtures of PUMand binder are described in Examples 10 and 11.

Example 10 NaOH-Neutralized Blend PUM and an Emulsion Polymer

A compound as prepared in Example 3 (11.0 g) was added to deionizedwater (24.2 g) in a glass vial containing a magnetic stir bar, followedby addition of NaOH (50 wt. % solution, 1.1 g). The vial was sealed andthe mixture was heated with stirring to 85° C. for 1 h to obtain a stockdispersion of NaOH-neutralized PUM nanoparticles with a pH was 12.0, asolids content of 30.3% and an average particle size of 21.0 nm. NH₄OHsolution (0.13 g of a 28% NH₄OH solution) was added to control emulsion2 (23.05 g) to bring the pH of the control binder to 9.1. A portion ofthe stock PUM nanoparticle dispersion (9.5 g) was then added to thepre-neutralized control binder 2 ((60 BA/38 MMA/2 MAA, 23.18 g). Thefinal pH was found to be 9.1 and the solids content was 43.4%. An MFFTof 0° C., a Koenig hardness of 21.0 s and water whitening value of 10after 20 min of water exposure were obtained on a dried film from theemulsion.

Example 11 NH₄OH-Neutralized PUM and an Emulsion Polymer

A compound as prepared in Example 3 (10.05 g) was added to deionizedwater (14.1 g) in a glass vial containing a magnetic stir bar followedby addition of NH₄OH solution (9.0 g of a 28% NH₄OH solution). The vialand sealed and the mixture was heated with stirring to 85° C. for 1 h.The vial cap was loosened and the mixture was then heated at 75° C. foran additional 6 h with stirring to obtain a stock dispersion ofNH₄OH-neutralized PUM nanoparticles with a pH of 10.0, a solids contentof 30.3% and an average particle size of 23.0 nm. A portion of the stockPUM nanoparticle dispersion (9.0 g) was then added to control emulsion 2(23.04 g). The final pH was measured at 10.0 and the solids content was44.10%. An MFFT of 0° C., a Koenig hardness of 16.8 s and waterwhitening value of 3 after 20 minutes of water exposure were obtained ona dried film from the emulsion.

The composition of the present invention provides a way of preparinglatexes exhibiting low MFFT and high storage modulus as compared withlatexes that do not contain one or more structural units of PUMs.Example 6 and comparative example 1 illustrate this improvement: Whereasthe latex containing the PUM exhibited an MFFT of 0° C. and a storagemodulus of 100 MPa at 140° C., the latex of comparative example 1, whichdoes not include one or more structural units of the PUM, exhibited anMFFT of 7° C. and a storage modulus of 0.1 MPa at 140° C. The latexes ofthe present invention have the desired attributes of PUDs and acrylicbased latexes in a single formulation.

The invention claimed is:
 1. A compound of the following formula I:

wherein n is 1 to 20; R¹ is 1,6-hexanediyl,

wherein the dotted lines represent the points of attachment; R² and R³are each independently C₂-C₁₀ linear or branched alkanediyl groups,benzenediyl groups, benzenedimethanediyl groups, or cyclohexanediylgroups; X and Y are independently O or NR⁴, wherein R⁴ is H orC₁-C₆-alkyl, with the proviso that at least one of X and Y is NH;wherein one or both of A¹ and A² comprise carboxylic acid functionalizedgroups selected from the groups consisting of —C(O)—(Z)_(m)—R⁵;—CH₂CH(OH)(CH₂)_(p)COOH; and —CR⁷═CH—C(O)—O—(CH₂)_(p)COOH, wherein; R⁵is

R⁷ is H or CH₃; with the proviso that when one of A¹ and A² does notcontain carboxylic acid functional groups, the non-carboxylic acidfunctionalized group is selected from the group consisting of:—CH₂CH(OH)R⁶; —CR⁷═CH—C(O)—O—(CH₂)_(p)R⁸; —C(O)—Y′—(CH₂)_(p)R⁹; and—CH₂—CH₂—C(O)—O—R¹⁰; R⁶ is —CH₂-acrylate, or —CH₂-methacrylate; R⁸ is anacrylate group or a methacrylate group; R⁹ is an acrylate group or amethacrylate group; R¹⁰ is H or —CH₂CH═CH₂; wherein each R¹¹ isindependently a linear or branched C₁-C₁₅ alkyl group; Z is a remnant ofa nucleophile; Y′ is O or NR⁴; m is 0 or 1; and each p is independentlyfrom 2 to
 6. 2. The compound of claim 1 wherein X and Y are each NH; andn is from 2 to 10; wherein A¹ and A² are each independently—C(O)(O)_(m)—R⁵; —CH₂CH(OH)(CH₂)_(p)COOH; or—CR⁷═CH—C(O)—O—(CH₂)_(p)COOH.
 3. The compound of claim 2 wherein R¹ is

wherein the dotted lines represent the points of attachment; and R² andR³ are each independently linear or branched C₃-C₁₀-alkanediyl groups.4. The compound of claim 3 wherein A¹ and A² are —C(O)—R⁵.
 5. Thecompound of claim 2 wherein m is 0; and one of A¹ and A² is—CH₂—CH(OH)R⁶, wherein R⁶ is —CH₂-methacrylate or —(CH₂)_(p)—COOH,wherein p is 2 to
 6. 6. The compound of claim 2 wherein at least one ofA¹ and A² is —CR⁷═CH—C(O)—O—(CH₂)_(p)R⁸; wherein R⁷ is H, R⁸ is COOH,and p is 2 or
 3. 7. The compound of claims 1 wherein one of A¹ and A² is—C(O)—O—(CH₂)_(p)R⁹, wherein R⁹ is a methacrylate group; and wherein theother of A¹ and A² is —C(O)CH₂CH₂COOH.
 8. A composition comprising anaqueous nanodispersion of the compound of claim
 1. 9. The compound ofclaim 2 where m is 0.